Graphic display system

ABSTRACT

A graphic display system including separate means for storing a representation of a value to be graphically displayed and a reference value which is less than the value representation. The reference value is incremented in steps of predetermined amounts and compared with the stored representation. When a match is detected, a predetermined change is caused in the display on a display device. This change may be the generating of a dot on the display, the initiating of a line, the terminating of a line, or the like.

I United States Patent n51 3,648,270

Metz et al. 51 Mar. 7, 1972 [54] GRAPHIC DISPLAY SYSTEM 3,522,597 8/1970Murphy ..340/324 A [72} Inventors: Robert Lee Metz, Nichols; Carl Green-3396'377 8/1968 snout ""340/324 blum, Stamford b ofcmm 3,406,387 10/1968Werme.. ....340/324 3.469.252 9/1969 Bet ....340/324 [73] Assignee: TheBunker-Ramo Corporation, Stamford, 3,474,438 10/1969 Lauher ..340/324Conn.

- Primary Examiner-Thomas B. Habecker [22] Filed 1969 AssistantExaminer-Marshall M. Curtis [21] Appl. No.: 848,901 Attorney-Fredrick M.Arbuckle [52] us. Cl. ..s4o/s24 A, 340/154 [571 ABSTRACT [51] Int. Cl..G06l 3/14 A graphic dismay system indudins "pm-ate means for storing[58] Field ofSeareh ..340/324 A, I725, I52, I54; 8 reprmmmion of a valueto be mphicauy displayed and a 235/1505 reference value which is lessthan the value representation. The reference value is incremented insteps of predetermined [56] Rfl'rem cued amounts and compared with thestored representation. When UNITED STATES PATENTS a match is detected, apredetermined change is caused in the display on a display device. Thischange may be the generating 3,199,883 4/1965 Farrow ..340/324 A of adot on the display, the inifiafi g f a he, the cn'njnah'ng 3,098,2197/1963 Voight et al. ..340/324 A fa |ine or the m 3,344,406 9/1967 Vinal340/1725 3,452,297 6/1969 Kelly et al... ..235/150.5 35 Claims, 11Drawing Figures l2 I4 352 I0 I VI 2 +2 |DNT vu I4 |/2| w 0 l2 I v 9 K)V2: v a B CLOSE PR I V 7 6 l/Z I o o v a 4 i H a m m 1 1 v 4 .L v s 1 Iv 2 l v 1 I Patented March 7, 1972 8 Sheets-Sheet 1 m: m: FI @I nIvI m1MI I QNInNINNENZONIQIQICIQIQIEIDINE :IQI WI mI NI m1 m1 #1 n1 MI IGIIIJFQDIOW INVENTOR ATTORNEY GRAPHIC DISPLAY SYSTEM This inventionrelates to a system for displaying a graphic representation of a valueand more particularly to a cathoderay tube (CRT) display system which iscapable of displaying a graphic representation of a plurality ofsuccessively received values.

Display devices, such as CRTs, are becoming increasingly popular asoutput terminals for general and special purpose computers. Thesedevices permit the user to either observe the results of variouscomputer operations or to view selected information contained in thecomputer's memory. When used in conjunction with a keyboard, thesedevices permit the user to engage in a dialogue with the machine. Whileterminals of this type may be utilized at the computer site, they arefrequently located at some distance from the computer and communicatewith the computer over telephone or other lines.

Copending application, Ser. No. 703,052 entitled "Information Storageand Display System," fried Feb. 5, I968, now US. Pat. No. 3,573,732 onbehalf of C. Greenblum et al. and assigned to the assignee of theinstant application shows a CRT display system of this type. In thissystem, alpha-numeric information is transmitted from a central stationto a remote station, selectively stored at the remote station, anddisplayed in alpha-numeric form on request. One such display, forexample, includes a listing of the price and volume for a number ofpreceding transactions on a elected stock. By viewing this information,the user can observe various trends on the particu- Iar stock. However,trends are more easily viewed from a graphic representation of thevalues.

l-ieretofore, graphic display on a CRT have generally been obtained byuse of a TV raster. Such a display, however, requires the transmissionof information for each individual dot on the screen. Thus, a display ofthis type, even if relatively coarse, requires a substantialtransmission bandwidth.

It would be preferable if a graphic display could be generated from thesame data base as is, for example, utilized to generate thealpha-numeric display in the before-mentioned Greenblum et al.application. In such a system, only the values which are to begraphically represented would be transmitted and stored, and thesevalues would be utilized to locally generate the graphic display bycausing selected changes in the intensification of a beam as it traces apredetermined raster pattern on the CRT screen. Such a system should becompatible with existing alpha-numeric displays and should also beflexible enough so as to permit the display of a variety of graphicrepresentations such as a single line, various types of bar graphs, orcombinations of multiples of the above. Since the graph is generatedlocally, it permits the user to select the particular information whichhe wishes to have plotted rather than limiting the display to a singleplot being transmitted from a central source.

One problem with a system of the type indicated above is in theselecting of a proper scale factor. If too fine a scale is selected andrelatively large fluctuations exist, some values will be off scale andan accurate picture of what is happening will not be provided.Similarly, if too course a scale is used where the fluctuations are notvery great, the small differences between succeeding values will not beeasily perceived. It is therefore desirable to provide the system with ascale adjustment, preferably automatic, which will at all times permitthe system to be set for the finest scale adjustment which is compatiblewith the fluctuations in the received data.

It is therefore a primary object of this invention to provide a systemfor displaying a graphic representation of a stored value.

A more specific object of this invention is to provide a graphicrepresentation of a plurality of succeedingly received values so as toenable the viewer to easily observe developing trends.

A still more specific object of this invention is to provide a displaysystem of the type indicated above which requires only the values,representations of which are to be displayed, to be transmitted andstored, with the graphic display being locally generated.

justment capability so as to provide the optimum scale in each instancefor the range of data being displayed.

A still further object of this invention is to provide a display systemof the type indicated above which is capable of operating with the samedata base as that utilized for an alpha-numeric display of the same dataand which is generally compatible with such an alpha-numeric displaysystem.

In accordance with these objects this invention provides a system fordisplaying a graphic representation of a value on a display device whichincludes a means for storing a representation of the value. The systemalso includes a means of storing a reference value which is less thanthe stored representation and a means for incrementing the referencevalue in steps of predetermined amounts. The incremented reference valueis compared with the stored representation in a comparing means. When amatch is detected in the comparing means, a predetermined change iscaused in the display on the display device. If the display device is aCRT, the raster of which is a plurality of parallel vertical strokes ofa writing beam, the predetermined change indicated above may be themomentary intensifying of the beam to generate a dot on the CRT screen.If a bar graph is desired, the beam may be intensified on each strokestarting at the horizontal axis, with a successful comparisontenninating the intensification. Other possible implementations will bediscussed in the description to follow.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings.

[n the drawings:

FIG. I is an illustrative representation of the display for a preferredembodiment of the invention.

FIG. 2 is an illustrative representation of the display for a firstalternative embodiment of the invention.

FIG. 3 is an illustrative representation of a portion of the display fora second alternative embodiment of the invention.

FIGS. 4A-4E, when combined as shown in FIG. 4, form a schematic blockdiagram of a circuit for a preferred embodiment of the invention.

FIG. 5 is a schematic block diagram of additional circuitry required fora first alternative embodiment of the invention.

FIG. 6 is a schematic block diagram of additional circuitry required fora second alternative embodiment of the invention.

GENERAL DESCRIPTION OF PREFERRED EMBODIMENT FIG. I is a representationof the face of a cathode-ray tube (CRT) 10. lnforrnation is displayed onthis screen by tracing a plurality of parallel vertical strokes on thescreen and selectively intensifying the tracing beam at selected indexpoints along each stroke. The particular display shown is capable ofdisplaying twelve rows of alpha-numeric characters, which rows aredesignated VI-VIZ respectively, with 24 characters, the positions ofwhich are designated HI-HJA, in each row. For each character there aresix strokes, designated Isl-L6, and for each row, there are eight indexpoint or bit positions, designated 81-88.

The illustrative display shown in FIG. I is a display of the price forsucceeding transactions on a selected stock. This is the graphicequivalent of half of the stock list display shown in FIG. 5 of thebefore-mentioned Greenblum et al. application. In this display, fourcharacters, Vl2, Hill-l3, are designated to display an alphabeticindication of the given stock. A

horizontal axis is provided along the line V4, B1 and a vertical axisalong the line H6,L1. A numeric indication of the close price of thegiven stock on the preceding trading day is provided at VB,H4 and H5,while scale values are provided at V4-VI2, l-I4-H5. As will be seenshortly, these scale values may be changed to be compatible with therange of the values being displayed. At stroke H6,L2 there is a dot 12which indicates the close price of the stock on the preceding day. Thesucceeding stroke position through H24, L6, each have a single dot I4indicating the price of a particular transaction. Each time a newtransaction occurs, the value of this transaction is displayed at H24,L6, with all other values except the close price being shifted lefi oneposition. The value which was previously displayed on stroke H6, L3 islost. It should be noted that because of the difference in size betweenFIG. I and a nonnal CRT screen, it has only been possible to show thedots on the LI strokes in the FIG. However, it should be understood thata dot will appear on each stroke providing a substantially continuousline on the display screen.

In general, the display of FIG. I is generated by initially taking theclose price and reducing it by an amount such that the resulting valueis less than the minimum value to be displayed with the scale factorbeing utilized. The values to be displayed are then transferred insuccession into a first compare register with the reduced close pricebeing at the same time transferred into a second compare register. Thereduced close price is then incremented in steps which are compatiblewith the scale being utilized in synchronism with the movement of thewriting beam on a stroke. When the quantities in the two compareregisters are equal, the beam is momentarily intensifted causing a dotto be generated on the stroke. If a dot ap pears in V3 or VI2, the scalefactor is increased.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 4A4E, when combinedas shown in FIG. 4, form a block diagram of a circuit for generating adisplay of the type shown in FIG. l. Referring first to FIG. 40 it isseen that the system includes a clock circuit I8. One input to thiscircuit is bit clock line 20. This line is applied to a bit clockcounter 22 and to a divide-by-eight circuit 24. The bit clock on lineoccurs in synchronism with the scanning of the CRT beam past each bit(or index point) position (see FIG. I). A means of controlling thissynchronism will be described later. Bit counter 22 indicates theparticular bit of a stroke which the beam is adjacent to at eachinstant. Since there are eight bits for each V position, output line 26from divider 24 is the V clock line. Line 26 is applied as an input to Vclock counter 28 and to divide-by-twelve circuit 30. V clock counter 28pro vides an indication of the V position of the writing beam on eachstroke. Since there are 12 V positions on each stroke, output line 32from divide-by-twelve circuit 30 is the line or stroke clock. This lineis connected as the step input to line clock counter 34 and as an inputto divide-by-six circuit 36. Line clock counter 34 provides anindication of the stroke which is being perfonned by the writing beam atany given time. Since there are six strokes to each H or character position, output line 38 from divide-by-six circuit 36 is the H clock line.This line is connected as the step input to H clock counter line. Thisline is connected as the step input to H clock counter 40. Clock counter40 provides an indication of the H position of the writing beam at anygiven time. In order to simplify the drawing, no attempt has been madeto connect the various clock outputs described above to the points inthe circuit of FIGS. 4A-4E at which they are utilized. Instead, at eachof these points, a line appears with the appropriate letter and numberdesignations for the clock or clocks which are utilized at that point inthe circuit.

As in the circuit of the before-mentioned Greenblum et al. application,stock identification and price information is applied to the circuitover a line 42 (FIG. 4A). This line may, for example. be one of theticker lines which is provided by the various stock exchanges, or may bea special line which contains selected transaction information such aslast price, volume, high price, low price, and the like. To simplify thepresent description it will be assumed that line 42 contains only anidentification of a stock on which a transaction has occurred followedby a transaction price. The manner in which desired information may beobtained with a more sophisticated line is for example described in thebefore-mentioned Greenblum et al. application.

An [.D. for the stock on which information is to be displayed is storedin [.D. register 44. This register may, for example, be loaded from akeyboard 138 (FIG. 4B) in a standard manner. The data on line 42 is alsoapplied to ID. register 46. The contents of registers 44 and 46 arecompared in compare circuit 48. A signal appears on control line 50 whena complete stock ID. is in register 46. The signal on line 50 may, forexample, be a line clock signal. When a match is detected in circuit 48at a time when a signal appears on line 50, a signal appears on line 52conditioning gate 54 to pass the following price information on line 42through line 56 to be stored in input data register 58. When the datahas pamed, the signal on line 52 terminates.

The system also includes a memory 60 (FIG. 4C) which may, for example,be a rotating magnetic drum. The succeeding prices which are to bedisplayed on CRT 10 are stored on a single track memory 60. This trackcontains a write marker which indicates the memory position in which thenext value is to be written. Each time a value is written into memory,this marker is advanced to the next succeeding memory position. Thismarker advance operation is performed in a standard manner which doesnot form part of the present invention. Memory 60 rotates at a speedsuch that information is read from the track of the memory insynchronism with the writing of the data on CRT [0. Therefore, theclocks from clock circuit l8 apply equally for the memory and thedisplay. In fact, the bit clock on line 20 may be derived from a clocktrack on the memory drum.

Each time a write marker is detected on the track of memory 60, causinga signal to appear on marker line 62, and V clock counter 28 isgenerating an output on a line VI2, VI, V2 or V3, AND-gate 64 (FIG. 4A)is fully conditioned to generate an output signal on line 66. Thissignal fully conditions gate 68 to pass any information in input dataregister 58 through line 70, gate 68, line 72, OR-gate 74, and writeline 76 to be recorded in memory 60. New infomration is, in this manner,loaded into the memory. Memory 60 also has a separate one-per-revolutionclock track 80. When the system is initialized, a signal appears oninitialize line 82. This signal, in conjunction with L6 and H24 clocksignals, fully conditions AND-gate 84 (FIG. 4A) to generate an outputsignal on line 86 which is applied through OR-gate 88 and write line 90to initially write the one-per-revolution clock bit in the last strokeposition. At the end of each drum revolution, the bit is read andapplied through line 9| to resynchronize the clock counters of clockcircuit 18.

When new information is loaded into memory 60, a signal appears on loadline 92. This signal may, for example, be an output from a flip-flopwhich is set when new information is loaded into the memory. The signalon line 92, in conjunction with H24 and L5 clock signals, fullyconditions AND-gate 94 (FIG. 4A) to generate an output on line 96 whichis applied to set advance flip-flop 98 to its ONE state. The signal onONE- side output line 100 from advance flip-flop 98 is applied as oneinput to AND-gates 102 and 104. During the next line time, L6, H24,AND-gate 102 is fully conditioned to generate an output signal on lineI06 which is applied to erase the oneper-revolution clock bit on track80. It should be noted, however, that before this bit is erased, it isread and utilized to resynchroniae clock I8. Therefore, during the nextrevolution of drum 60, clock I8 will be operating in synchronism withthe old one-per-revolution bit. During the next stroke time, H1, Ll,AND-gate 104 is fully conditioned to generate an output signal on lineI08 which is applied through OR gate 88 and line 90 to write a newone-per-revolution clock on track 80. As will be seen shortly, theadvancing of the one-per-revolution clock is effective to perform therequired shifl-lett operation when a new value is stored in the memory.

Once a day, prior to the start of trading, line 42 contains the closeprice for the preceding trading day for the various stocks. When thisclose price is loaded into input data register 58, a signal also appearson close-price line I10. This line conditions gate 112 (FIG. 48) to passthe close price on line 70 through line 114 OR-gate 116 and line 118into register 120. The close signal on line 110 is also applied as oneinput to AND-gate 122. At clock times V12, L2, H4, H5 and H6 AND- gateI22 is fully conditioned to generate an output signal on line 124 whichis applied through OR-gate I26 and line 128 to condition gate 130 topass the contents of register 120 on line 132 through gate 130, line134, OR-gate 74 and line 76, to be written in memory 60. The close priceshown in FIG. 1 is in this manner obtained. It should be noted that theclose price is written in memory twice. It is written at H4 and H5 tocause a numeric display of the close price, and at H6 to cause thegeneration of the close price dot 12.

It is apparent that, since close prices appear on line 42 only once aday, the stock on which a graphic display is being obtained cannot bechanged during the course of a single day with the embodiment shown.However, the before-mentioned Greenblum et al. application teaches howseveral close prices may be stored on drum 60 for future use. A systemcould also be designed where the close price on a selected stock wouldbe available on line 42 in response to an input request.

The final input to memory 60 is obtained from keyboard I38 (FIG. 4B).This keyboard is used to indicate the ID for the stock which is havingits prices graphically displayed and, in addition to being used to loadmemory 60, may also be used to load [D register 44. As each character isgenerated from keyboard 138, coded signals appear on lines 140, whichsignals are applied through OR-gate I16 and line 118 to be stored inregister 120. When a key is depressed on keyboard 138, a signal appearson keyboard line 142. This signal may, for example, be obtained by ORingthe outputs on lines 140. This signal on line 142 is applied as oneinput to AND-gate 144. The other inputs to AND-gate 144 are clock linesV12, L2 and H-13. Output line 146 from AND-gate 144 is applied throughOR-gate 126 and line 128 to condition gate 130 to pass the stock ID inregister 120 through line 134 to be stored in memory 60. From FIG. 1 itwill be seen that the positions in which the IDs are loaded are the sameas those in which the IDs are displayed. The manner in which thesestored characters are utilized will be described shortly.

Before describing the manner in which the dots 12 and 14 are generated,one additional load operation should be described. As was indicatedpreviously, the information stored in memory 60 is shifted left oneposition by advancing the oneper-revolution clock on track 80 which isused to synchronize clock 18. However, while it is desired to shift thevalue information in memory 60, it is not desired to shift thealpha-numeric infonnation for the stock ID and the close price, nor isit desired to shifl the dot I2. In order to prevent this from happening,these characters are effectively shifted right one stroke positionduring the first memory cycle after the rewriting of theone-per-revolution clock. It will be remembered from previous discussionthat during this cycle the clock is still operating under control of theprevious one-per-revolution marker.

During L2, H4, H5 and H6 time of this memory cycle, AND-gate 150 isfully conditioned to generate an output on line 152 which is applied tocondition gate 154 to pass the close price then being read from memory60 through line 156, conditioned gate 154, and line 158, into register120. At this time, advance flip-flop 98 (FIG. 4A) is still in its ONEstate causing a signal to appear on advance line 100 which signal isapplied as one input to AND-gate 160 (FIG. 4B). The other inputs to thisAND-gate are clock lines V12, L3, and H4, H5 and H6. Therefore, onestroke time after each character of the close price is loaded intoregister 120, AND-gate 160 is fully conditioned to generate an outputsignal on line 162 which is applied through OR-gate I26 and line 128 tocondition gate to rewrite the character then in register 120 in memory60. The desired one-stroke shift-right of the close price. including theclose price dot I2, is in this manner effected. The writing of the closeprice value in H6, L3, efl'ectively erases the oldest value previouslybeing displayed, which value was stored in that position. Similarly.during L2, HIO-Hl3, AND- gate is conditioned to pass the ID charactersthen being read from memory 60 through gate 154 to be stored in register120. The signal on line 100 is also applied as a conditioning input toAND-gate 164. One stroke time after each of the ID characters is loadedinto register 120, AND-gate 164 is fully conditioned to generate anoutput signal on line 166 which is applied through OR-gate 126 tocondition gate 130 to pass this character back into memory 60. Thedesired shift-right of the ID characters is in this manner efiected.

During H4 and H5 time of each revolution of memory 60, the close pricestored in memory is gated through gate 154 into register 120. At V10time of H4 and H5, AND-gate 170 (FIG. 4B) is fully conditioned togenerate an output on line 172 which is applied to condition gate 174 topass the clock price in register 120 through line 176, gate 174and line178 to be stored in register 180. During VI 1 and V12 time ofHS, L2, theclose price in register 180 is counted down under control of signals online 182 from count-down control circuit 184. In addition to the clocksindicated above, which indicate when the count-down is to be performed,count-down control circuit 184 also has as inputs bit clock line 20,which is the clock input for the count-down, and range control lines192, 194, and 196.

As was indicated previously, the scale factor utilized on the display isautomatically controlled to be the first scale commensurate with therange of received data. For the illustrative embodiment shown in FIGS.4A-4E, three possible ranges are possible, :2, :4 or 1-8. The :4 rangeline 194 is the ONE-side output from 14 flip-flop 198 (FIG. 4B). The 1-8range line 196 is the ONE-side output line from :8 flip-flop 200.ZERO-side output lines 202 and 204 from flip-flops 198 and 200respectively are connected as the inputs to AND-gate 206. Thus, when thecircuit is in neither :4 nor in 18 range, AND-gate 206 is fullyconditioned to generate an output on :2 range line 192. Initialize line82 is applied through OR-gate 208 and line 210 to the ZERO-side input offlip-flop 198, and through OR- gate 212 and line 214 to the ZERO-sideinput of flip-flop 200. Therefore, the circuit is initially set tooperate in the fl range with a signal on line 192. The manner in whichthe circuit adjusts to display information with different ranges will bedescribed shortly.

Range inputs 192-196 thus determine how much the close price in register180 will be counted down for each received bit clock. As was indicatedpreviously, the total amount by which the register is counted down willbe sufficient to bring the price well below the horizontal axis. Forexample, the price may be counted down sufficiently to bring it to thelevel represented by a dot V3, BI for the range selected.

At VI of each stroke, the counted down close price in register 180 (FIG.4C) is transferred through conditioned gates 220 to a first compareregister 222. During V3-V12 of each stroke, the reduced close price inthis register is counted up under control of signals on output line 224from count-up control circuit 226. Again, a count-up occurs for each bitclock on line 20 with the amount by which the count in register 222 iscounted up for each clock being controlled by the range signals on lines192496. In each instance the amount by which the count in register 22 iscounted up for each bit clock is equal to the increment in pricerepresented by each bit. Thus, with a range of t2, the count upoperation would be by l6ths. With a range of t4, the count-up would beby eights while with the range of fl, the count-up would be by quarters.

Each time the one-per-revolution clock is detected on track 80, GRFflip-flop 230 (FIG. 4C) is reset to its ZERO state. At

the following H6 time, this flip-flop is set to its ONE state. Theresulting GRF signal on ONE-side output line 232 from this flip-flop isapplied as one input to AND-gate 234. At each succeeding V1 and V2 time,AND-gate 234 is fully conditioned to generate an output signal on line236 which is applied to condition gate 238 to pass the output frommemory 60 on line 156 through line 240 to be stored in a second compareregister 242. It will be remembered that the close price, in addition tobeing stored at H4 and H5, is also stored at H6, L2. The first valueread into register 242 is thus the close price. This price is comparedagainst the incremented values in register 222 in compare circuit 244.When the quantities in registers 222 and 242 are equal, compare circuit244 generates a signal which will be referred to as the DOT signal online 246. The Dot signal is applied through OR-gate 248 (FIG. 4D) andline 250 to display device to cause the dot 12 to be recorded on theface of CRT 10. Display device 10' includes CRT 10 and its relatedcontrol circuitry.

The close price of stroke H6, L2 is followed during the next stroke timeby the first price to be displayed by a dot 14. Since GRF flip-flop 230(FIG. 4C) remains in its ONE state until the end of the drum revolution,during V1 and V2 time of this following stroke, gate 238 is conditionedto pass this price into register 242. During V1 time, gate 220 isconditioned to pass the counted-down close price in register 180 intoregister 222. Starting at V3 time, this price is again counted up andcompared in compare circuit 244 with the price now stored in register242. When compare circuit 244 detects a match between these quantities,a Dot signal again appears on line 246 resulting in a dot 14 beingrecorded on the face of CRT 10. During each succeeding stroke, a newvalue is transferred into register 242, the counted-down close price istransferred into register 222, and the quantity of register 222 isincremented in steps of predetermined length. When the quantity inregister 222 is incremented to a value equal to that stored in register242, a Dot signal appears on line 246, resulting in the desired dot l4appearing on the CRT. The display shown in FIG. I is in this mannerobtained.

It should be noted that in addition to line 246, output line 254 fromaxis generator 256 (FIG. 4D), and output line 258 from charactergenerator 260 are also inputs to OR-gate 248. Axis generator 256 has asinputs thereto the clock signals for the axis selected. For example, forthe axis shown in FIG. 1, the inputs to generator 256 would be V4, B1and H6, L1. Character generator 260 is a device which convertscharacters coded in a transmission or storage code, such as ASCII, intothe equivalent video coded character. One input to character generator260 is output line 262 from special character generator 264. Generator264 could, for example, be utilized to generate the scale referenceshown in FIG. 1. In order to obtain the proper scale reference, rangelines 192-196 are applied as inputs to this generator. In addition,clocks would be applied as inputs to this generator to assure that therange characters were displayed at proper display positions.

The other input to character generator 260 is output line 266 from gate268 (FIG. 4C). The information input to gate 268 is output line 132 fromregister 120 (FIG. 48). It will be remembered that gate 154 isconditioned by outputs from AND-gate 150 to store both the close priceand the stock ID in register 120 during appropriate clock times. Gate268 is conditioned by a signal on output line 270 from OR-gate 272. Theinputs to OR-gate 272 are output line 274 from AND-gate 276 and outputline 278 from AND-gate 280. The inputs to AND- gate 276 are V8 andH4-I-I5. From FIG. 1 it is seen that these are the coordinates at whichthe close price is displayed. Similarly, the inputs to AND-gate 280 areV12, H10-H13. From FIG. 1, it is seen that these are the positions atwhich the stock identification characters are displayed. Thus, atappropriate times in the display cycle, the close-price characters andthe stock identification characters are applied to character generator260. This results in the display of these characters on the CRT screen.

As was indicated previously, range flip-flops 198 (FIG. 4E) and 200 areoriginally reset, resulting in an output on :2 range line 192. If a dotis detected outside this range, for example in V3 or V12, then the rangeis too fine and must be expanded. This is accomplished by applying theDot output on line 246 as one input to AND-gate 284, the other input tothis AND-gate being output line 286 from OR-gate 288. The inputs to OR-gate 288 are the V3 and V12 clock line. Thus, AND-gate 284 is fullyconditioned when a dot appears in either V3 or V12. Output line 290 fromAND-gate 284 is connected to the ONE- side input of flip-flop 292.ONE-side output line 294 from fliptlop 292 is connected as one input toAND-gates 296 and 298. The H1 clock line is a second input to each ofthese AND gates. The final input to AND-gate 296 is :LZ line 192, andthe final input to AND-gate 298 is 114 line 194. Therefore, AND gate 296is fully conditioned at the first H1 time after flip-flop 292 is set ifthe circuit is operating in the 22 range. Output line 300 from AND-gate296 is applied through OR-gate 302 and line 304 to set flip-flop 198 toits ONE state. The range is in this manner expanded from 1'2 to :4.Similarly, if the circuit is in :4 range, at the first H1 time afterflip-flop 292 is set to its ONE state, AND-gate 298 is fully conditionedto generate an output signal on line 306 which is applied to setflip-flop 200 to its ONE state. The range is in this manner expandedfrom :4 to fl.

Since, atter fluctuating widely for a period, the price may againstabilize, it is also desirable to have the capability to reduce therange. For example, if it is found that there is no dot in V4, V5, V11,or V12, then the range may be safely reduced without losing any of thedots. This reduction is accomplished by applying Dot line 246 as oneinput to AND- gates 310 and 312. A second input to each of these ANDgates is output line 314 from OR-gate 316. The inputs to OR-gate 316 arethe V4, V5, V1] and V12 clock lines. The final input to AND-gate 310 is:4 range line 194 and the final input to AND-gate 312 is :8 range line196. Thus, AND-gate 310 is fully conditioned if the circuit is in :4range and a dot is located in V4, B5, V11 or V12. Similarly, AND-gate312 is fully conditioned if the circuit is in i8 range and a dot islocated in one of the four positions indicated above. Under theseconditions, no range change is desired. Therefore, output lines 318 and320 from AND-gates 310 and 312 respectively are connected throughOR-gate 322 and line 324 to set flip-flop 326 to its ONE state.Flip-flop 326 is reset to its ZERO state by an H2 clock. ZERO-sideoutput line 328 from flip-flop 326 is connected as one input toAND-gates 330 and 332. A second input to each of these AND gates is theH1 clock line. The final input to AND-gate 330 is :8 range line 196,while the final input to AND-gate 332 is :4 range line 194. Therefore,AND-GATE 330 is fully conditioned at H1 time if the circuit is in 1'8range and a dot has not been detected in one of the four V positionsindicated above. Output line 334 from AND-gate 330 is connected throufliOR-gate 212 to reset flip-flop 200 to its ZERO state and through OR-gate 302 to set flip-flop 198 to its ONE state. The range is, in thismanner reduced from 1'8 to :4. Similarly, AND-gate 332 is fullyconditioned at H1 time if the circuit is in :4 range and a dot does notappear in one of the four positions indicated above. Output line 336from AND-gate 332 is connected through OR-gate 208 to reset flip-flop198 to its ZERO state. This effectively restores the circuit to :2range.

A system has thus been described for generating a combined alpha-numericand graphic display of a succession of related values. The circuit iscapable of recording a single dot for each value and of shifting thedisplay in order to accommodate new information. Finally, the circuit iscapable of adjusting the range of the display both up and down in orderto provide the optimum range for any set of values to be displayed.

GENERAL DESCRIPTION OF FIRST ALTERNATIVE EMBODIMENT As was indicatedpreviously, the display of FIG. 1 contains only half the informationwhich was contained in the display of FIG. of the before-mentionedGreenblum et al. application. FIG. 2 illustrates a display format whichis adapted to provide information both as to the price and volume foreach transaction. In this display, the dots I2 and 14 appear much asthey did in the embodiment of FIG. 1. However, in addition, each strokealso includes a bar 350 the height of which indicates the volume of thetransaction. The display of FIG. 2 also includes the axis, I.D., closeprice, and price range shown in FIG. 1. In addition, the embodiment ofFIG. 2 also includes a volume range. While this range may be expanded orcontracted by detecting bar height in much the same way that the pricescale is expanded and contracted, specific circuitry for performing thisfunction will not be shown. Referring still to FIG. 2, it is noted thatat points 352 at which a dot l4 intersects a bar 350, a blank spaceappears. This is the method which has been selected in this embodimentof the invention for illustrating the combined occurrence of a dot and aline at the same bit position. Other means, such as a flashing dot or ahorizontal bar, could also be utilized.

The dots 14 in FIG. 2 are generated in a manner substantially identicalto that of the dots shown in FIG. I. The only difference involves theblanking of a dot when it coincides with a bar 350. The generating ofthe bars is complicated slightly by the fact that volume is assumed tobe cumulatively received. Thus, each time a new cumulative volume isreceived, it is stored in a first compare register, and the previouslystored cumulative volume is transferred to a second compare register.The contents of the second compare register is then incremented insynchronism with the tracing of the bar 350 on the face of CRT 10. Whena match is detected between the volumes stored in the two compareregisters, the intensifying of the writing beam is terminated.

DETAILED DESCRIPTION OF FIRST ALTERNATIVE EMBODIMENT In the same mannerthat the price for each stock transaction is recorded on a track ofmemory 60, volume may also be recorded. Each volume figure would appearin a corresponding clock position on an adjacent track to the price forthe given transaction. As was indicated previously, at H6, Ll, GRFflip-flop 230 (FIG. 4C) is set to its ONE state resulting in an outputsignal on GRF line 232. At each VI and V2 time thereafter, AND-gate 356(FIG. 5) is fully conditioned to generate an output signal on line 358which signal is applied to condition gate 360. The volume output from avolume track of memory 60 is applied through line 362, conditioned gate360, and line 364 to be stored in volume register 366. As was indicatedpreviously, this is a cumulative volume for all transactions up throughthe indicated one for a given day. As a new volume is being shifted intoregister 366, the previous volume stored in this register is shifted outthrough line 368 into cumulative volume register 370.

During the following V4-V9 time, the count in register 370 isincremented under control of signals on line 372 from counter controlcircuit 374. Circuit 374 effectively gates the bit clocks on linethrough to increment the count in counter 370 during V4-V9 time. Itshould be noted that no means is provided in this circuit forcontrolling the amount by which the count is incremented. However, suchcircuitry could be provided, if desired, in much the same manner as itis provided in FIGS.4A-4E.

The counts in registers 366 and 370 are continuously compared in comparecircuit 376. When these counts are equal, compare circuit 376 generatesan output signal on line 378 which is applied through OR gate 380 andline 382 to reset flip-flop 384 to its ZERO state. As will be seenshortly, this effectively terminates the writing of a line 350.

Flip-flop 384 is set to its ONE state by a signal on output line 386from AND-gate 388. The inputs to AND-gate 388 are GRF line 232, anH-axis clock line, and output line line 390 from inverter 392. Thus,flip-flop 384 is set to its ONE state each time a stroke after H6, Llcrosses the H-axis, provided that a successful comparison is notoccuring at that time at compare circuit 376.

Referring sdll to FIG. 5, it is seen that the OR-gate 248 of FIG. 4D hasbeen replaced by an OR-gate 248, the inputs to which are the same asthose in FIG. 4D except that the single Dot input line 246 has beenreplaced by two lines. These lines are output line 394 from AND-gate 396and output line 398 from AND-gate 400. The inputs to AND-gate 396 areDot line 246 and ZERO-side output line 402 from flip-flop 384. Thus, adot 14 will be written on the display when there is a signal on Dot line246 and flip-flop 384 is reset indicating that a line 350 is not to bedrawn. The inputs to AND-gate 400 are output line 404 from the ONE-sideof flip-flop 384, no Dot line 406 and a clock line 408 which has asignal on it where the circuit is not on stroke H6, L1 or stroke H6, L2.The reason for inhibiting the writing of a volume stroke during strokeH6, Ll is that this is the stroke on which the vertical axis is drawnand, therefore, no volume is stored or displayed during the stroke.During H6, L2, a volume corresponding to the price which was overwrittenby the close price is written into in register 366, but there is nomeaningful volume figure in register 370 against which to compare it.Therefore, the volume display is again inhibited. This inhibiting isalso proper since the H6, L2 stroke is the stroke during which the closeprice dot I2 is recorded.

It is thus seen that the writing of a line 350 is started when a strokeafter H6, L2 crosses the horizontal axis and continues until asuccessful comparison is had in compare circuit 376. It should be notedthat if a successful comparison does not occur before then, the VI]clock is applied through OR-gate 380 to reset flip-flop 384. Thisprevents a line 350 from going off the screen. It should also be notedthat if, during the writing of a line 350, a Dot signal appears on line246, this terminates the signal on line 406 effectively inhibiting thewriting of a dot on the display and resulting in a blank space 352.

GENERAL DESCRIPTION OF SECOND ALTERNATIVE EMBODIMENT A third type ofgraph which is frequently employed in the financial community is onewhich shows the range of price for a particular stock over a unit oftime such as a day, week, month, etc. Such a graph may also include,somewhere along the range line, an indication of the last price for theitem during the indicated period.

FIG. 3 illustrates the first few lines of such a graph. Each line 420starts at the low price for the stock on, for example, a given tradingday, and ends at the high price of the stock during the same day. Ahorizontal line 422 appears at the point along line 420 at which thestock closed on the given day. The reference price for the display maybe the close price of the stock on the last trading day preceding theperiod being displayed, or the reference may be some other selectedvalue.

To generate a display of the type shown in FIG. 3, the axis, scales,I.D's and the like would be generated in the same manner as for theembodiment of the invention shown in FIG. 4. High price, low price, andlast price for the selected period would be stored in correspondingclock positions on difierent tracks of memory drum 60. Each of thesevalues would be read into a corresponding register and compared againstan incremented value which starts lower than the lowest value which isto be displayed. When the incremented value matches the low price, theintensification of the writing beam begins. A special indication, suchas a blinking dot, horizontal line, blank space, or the like is providedwhen the incremented value equals the last price, and the intensifyingof the beam is terminated when the incremented value equals the highprice.

DETAILED DESCRIPTION OF SECOND ALTERNATIVE EMBODIMENT FIG. 6 is aschematic diagram of a circuit for generating a display of the typeshown in FIG. 3. Unlike the displays previously described, this displayappears only on every other line, in this instance the even numberedlines L2, L4, and L6. During the odd line times, Ll, L3, and L5, asignal appears on line 426. These signals are applied to condition gates431433 to pas the high price, last price, and low price respectively onlines 436-438 from the appropriate tracks on memory 60 through lines441-443 to be stored in buffers 446-448. The contents of buffers 446-448are applied through lines 451-453 respectively as one set of inputs tocompare circuits 456-458. The other set of inputs to each of thesecompare circuits are output lines 460 from register 222. Referring backto FIG. 4C, it will be seen that register 222 is the register in whichthe incrementing of the previously reduced close price is performed.

When the price in register 222 equals the low price in buffer 448,compare circuit 458 generates an output signal on line 462 which isapplied as one input to AND-gate 464 and through inverter 466 as oneinput to AND-gate 468. The other inputs to AND-gate 464 are even clockline 470 and output line 472 from inverter 474. The input to inverter474 is a match output line 476 from high-price compare circuit 456.Output line 478 from AND-gate 464 is applied to the ONE- side input offlip-flop 480. ONE-side output line 482 from flipflop 480 is appliedthrough OR-gate 248" to line 250 leading to display device 10'. It isthus seen that the match in compare circuit 258 results in theintensifying of the beam then being traced on display screen 10.

When the value in register 222 equals that in last price buffer 447,compare circuit 457 generates an output signal on line 484 which isapplied to trigger special symbol generator 486. Special symbolgenerator 486 may, for example, cause a high frequency horizontalwaveform to be momentarily impressed on the raster generating circuitry,or may cause the blinking of the spot in a manner similar to thatdescribed in the before-mentioned Greenblum et a1. application. In anyevent, it causes the appearance of this dot to be different from thoseon the remainder of the line 420. Output line 488 from generator 486 isapplied through OR-gates 248' to line 250.

Finally, when the value in register 222 equals the value in high-pricebuffer 446, compare circuit 456 generates an output on line 476 which,during an even line time, fully conditions AND-gate 468 to generate anoutput signal on line 490. This signal is applied to reset flip-flop 480to its ZERO state, thus terminating the input to OR-gate 248". Theintensifying of the beam on display screen 10 is thus terminated.

A system has thus been described which is capable of graphicallydisplaying various stored values in a variety of differentconfigurations. The circuit is versatile in that the number ofquantities, the nature of the quantity, the nature of the display, andthe range of values to be displayed may be varied. Since a display islocally generated the operator may select the item on which he wishes adisplay, and another user, being served by the same data base, mayobtain a display of a different item. The data to be transmitted needcontain only the values without including graphic information and may beutilized for other purposes such as alpha-numeric display or the like.

In the above embodiments described above, a fixed reference value,namely the close price, has always been utilized. It is apparent thatsome other reference value, such as, for example, the open price or acomputed average price for the values displayed might be utilizedinstead as a reference value. Also, in the description above, the rangesabove and below the reference value have always been equal. With moresophisticated detection and control circuitry, the range variationsabove and below the reference value might be individually varied so asto further optimize the display range. Similarly, while specificelements have been described above for performing the display, storage,logic and other functions, it is apparent that functionally equivalenthardware or software elements might be utilized to perform each of thesefunctions. Thus, while the invention has been particularly shown anddescribed with reference to preferred embodiments thereof, it will beunderstood by those skilled in the art that the foregoing and otherchanges in form and details may be made therein without departing fromthe spirit and scope of the invention.

What is claimed is:

l. A system for displaying a graphic representation of a value on adisplay device of the type having a moving raster comprising:

means for storing a representation of said value;

means for storing a reference value which is initially less than saidrepresentation;

means for successively adding a predetermined quantity to said referencevalue in synchronism with the movement of said raster;

means operative each time said reference value is added to for comparingthe new reference value with said representation; and

means responsive to a match in said comparing means for causing apredetermined change in the display on said display device.

2. A system of the type described in claim 1 wherein said display deviceis a cathode ray tube (CRT).

3. A system of the type described in claim 1 wherein there are aplurality of said values to be graphically represented and includingmeans for applying representations of said values in succession to saidvalue representation storing means.

4. A system of the type described in claim 1 including means forindicating a selected range for said value representations;

means for detecting whether the values applied to said valuerepresentation storing means conform to such selected range; and

means responsive to a detection that the range of values applied to saidvalue representation storing means differs from said selected range forchanging the selected range.

5. A system of the type described in claim 4 including means responsiveto said range indicating means for controlling said predetenninedquantity.

6. A system of the type described in claim 5 wherein said rangedetecting means includes means for detecting whether a value applied tosaid value representation storing means is greater than or less than thevalues of said selected range; and

wherein said predetermined quantity controlling means includes meansresponsive to said detection for increasing said predetermined quantity.

7. A system of the type described in claim 5 wherein said rangedetection means includes means for detecting when the values applied tosaid value representation storing means during a predetermine timeperiod do not exceed in range a selected amount which amount is lessthan the range indicated by said range indicating means; and

wherein said predetermined quantity controlling means includes meansresponsive to said detecting means for decreasing said predeterminedquantity.

8. A system of the type described in claim 3 wherein there are a fixednumber of value representation display positions on said display device;and

including means responsive to an attempt to display a new value when allare said display positions of being med for displaying therepresentation of said new value in the display position previouslyoccupied by the most recently received of the displayed values, forshifting all of the displayed values one display pofltion in theappropriate direction, and for eliminating the oldest displayed valuefrom the display.

9. A system of the type described in claim 1 including means for varyingsaid predetermined quantity.

10. A system of the type described in claim 1 wherein said predeterminedchange causing means includes means for displaying a point on saiddisplay device.

11. A system of the type described in claim including means for storinga given value; and

means for decrementing said given value by a predetermined amount toobtain said reference value.

12. A system of the type described in claim 11 including means forcontrolling the amount by which said given value is decremented.

13. A system of the type described in claim 11 wherein said value is alast price value for aselected stock;

wherein said given value is the close price for said stock on thepreceding trading day;

and including means for applying succeeding last price values for saidselected stock to said value representation storing means.

14. A system of the type described in claim 13 including means forcontrolling the range of last prices which may be displayed on saiddisplay device.

15. A system of the type described in claim [4 wherein said rangecontrolling means includes means for controlling the amount by whichsaid given value is decremented, and means for controlling thepredetermined quantity successively added to the resulting referencevalue.

16. A system of the type described in claim 14 including means fordisplaying an alpha-numeric indication of the selected stock, the closeprice. and the range of values being displayed.

17. A system of the type described in claim 13 wherein there are a fixednumber of display positions on said display device at which a last-pricevalue may be displayed; and including means responsive to the receipt ofa new last price for said selected stock when all of said displaypositions are full for displaying the new value in the positionpreviously occupied by the most recently received of the displayedvalues, for shifting all the displayed values one display position inthe appropriate direction, and for eliminating the oldest displayedvalue from the display.

18. A system of the type described in claim 1 including means fordisplaying alpha-numeric information with said graphic representation.

19. A system of the type described in claim 1 wherein the normal displayon said display device is the drawing of a line; and

wherein said predetermined change causing means includes means forterminating the drawing of said line in response to a match in saidcomparing means.

20. A system of the type described in claim 19 including means fordefining a horizontal axis for said display;

means for tracing a vertical line on said display device starting atsaid horizontal axis; and

wherein said line drawing terminating means is operative to terminatethe drawing of said line.

21. A system of the type described in claim 20 wherein there are aplurality of said values to be graphically represented and includingmeans for applying representations of said values in succession to saidvalue representations storing means;

said line drawing means being operative to draw a line starting at saidhorizontal axis for each of said values. 22. A system of the typedescribed in claim 21 wherein two different sets of values are to besimultaneously displayed on said display device;

wherein one of said sets of values is displayed by drawing linesstarting at said horizontal axis which are terminated in response to amatch in a first comparing means; and

wherein said second set of values is represented by displaying a pointon said display device in response to a match in a second comparingmeans.

23. A system of the type described in claim 22 wherein said two sets ofvalues are related with corresponding values in each of said sets beingdisplayed on the same vertical line; and

including means for uniquely identifying a point where the two values ona common vertical line intersect.

24. A system of the type described in claim 23 wherein said means foruniquely identifying includes means for inhibiting the display at apoint where a point representing a value of said second set occurs on aline representing a line of said first set.

25. A system of the type described in claim 21, wherein the values to bedisplayed are applied to said system as a cumulative amount; andincluding means responsive to the receipt of a new value fortransferring the value in said value representation storing means tosaid reference value storing means.

26. A system of the type described in claim 22 wherein said first set ofvalues are volume values for succeeding transactions on a selectedstock; and

wherein said second set of values are last price values for saidtransactions.

27. A system of the type described in claim 1 wherein said graphicrepresentation is of two related values; and

including separate means for storing a representation of each of saidvalues;

means for comparing the added to reference value with each of saidrepresentations;

means responsive to a match between said added to reference value and athat of said stored representations for initiating the drawing of a lineon said display device; and

means responsive to a match between said added-to reference value andthe other of said stored representations for terminating the drawing ofthe line on said display device.

28. A system of the type described in claim 27 wherein said graphicrepresentation is of three related values;

wherein there is a separate one of said storing means and a separate oneof said comparing means for each of the three values; and includingmeans responsive to a match between said added-to reference value andthe third of said values for causing a unique mark to appear on saidline.

29. A system of the type described in claim 28 wherein said line is avertical line; and

wherein said unique mark is a short horizontal line intersecting saidvertical line.

30. A system of the type described in claim 28 wherein said three valuesare the low price, high price, and last price respectively for aselected stock during a predetermined period of time.

31. A system of the type described in claim 27 wherein said display isof at least two sets of related values; and including means for applyingsucceeding corresponding values from each of said sets in succession tothe appropriate value representation storing means.

32. in a CRT of the type having a raster scan with a plurality of indexpoint containing strokes for each row displayed on the CRT screen, asystem for displaying a graphic representation of a value comprising:

means for storing a representation of said value;

means for storing a reference value which is initially less than saidrepresentation;

means for successively increasing said reference value in steps ofpredetermined quantity in synchronism with said raster moving past theindex points of a stroke:

means for comparing the increased reference value with saidrepresentation; and

means responsive to a match in said comparing means for causing apredetermined indication to appear on said CRT at the index point beingscanned at the time of said match.

33. A system of the type described in claim 32 including means operativebetween the displayed portion of successive strokes for restoring theinitial reference value in said reference value storing means.

34. A method of displaying a graphic representation of a value on a CRTof the type having a raster scan with a plurality of index pointcontaining strokes for each row displayed on the CRT screen comprisingthe steps of:

storing a reference value which is initially less than saidrepresentation; successively increasing said reference value in steps ofpredetermined quantity in synchronism with said raster moving past indexpoints of a stroke; comparing the increased reference value with saidrepresen-

1. A system for displaying a graphic representation of a value on a display device of the type having a moving raster comprising: means for storing a representation of said value; means for storing a reference value which is initially less than said representation; means for successively adding a predetermined quantity to said reference value in synchronism with the movement of said raster; means operative each time said reference value is added to for comparing the new reference value with said representation; and means responsive to a match in said comparing means for causing a predetermined change in the display on said display device.
 2. A system of the type described in claim 1 wherein said display device is a cathode ray tube (CRT).
 3. A system of the type described in claim 1 wherein there are a plurality of said values to be graphically represented and including means for applying representations of said values in succession to said value representation storing means.
 4. A system of the type described in claim 1 including means for indicating a selected range for said value representations; means for detecting whether the values applied to said value representation storing means conform to such selected range; and means responsive to a detection that the range of values applied to said value representation storing means differs from said selected range for changing the selected range.
 5. A system of the type described in claim 4 including means responsive to said range indicating means for controlling said predetermined quantity.
 6. A system of the type described in claim 5 wherein said range detecting means includes means for detecting whether a value applied to said value representation storing means is greater than or less than the values of said selected range; and wherein said predetermined quantity controlling means includes means responsive to said detection for increasing said predetermined quantity.
 7. A system of the type described in claim 5 wherein said range detection means includes means for detecting when the values applied to said value representation storing means during a predetermine time period do not exceed in range a selected amount which amount is less than the range indicated by said range indicating means; and wherein said predetermined quantity controlling means includes means responsive to said detecting means for decreasing said predetermined quantity.
 8. A system of the type described in claim 3 wherein there are a fixed number of value representation display positions on said display device; and including means responsive to an attempt to display a new value when all are said display positions of bEing used for displaying the representation of said new value in the display position previously occupied by the most recently received of the displayed values, for shifting all of the displayed values one display position in the appropriate direction, and for eliminating the oldest displayed value from the display.
 9. A system of the type described in claim 1 including means for varying said predetermined quantity.
 10. A system of the type described in claim 1 wherein said predetermined change causing means includes means for displaying a point on said display device.
 11. A system of the type described in claim 10 including means for storing a given value; and means for decrementing said given value by a predetermined amount to obtain said reference value.
 12. A system of the type described in claim 11 including means for controlling the amount by which said given value is decremented.
 13. A system of the type described in claim 11 wherein said value is a last price value for a selected stock; wherein said given value is the close price for said stock on the preceding trading day; and including means for applying succeeding last price values for said selected stock to said value representation storing means.
 14. A system of the type described in claim 13 including means for controlling the range of last prices which may be displayed on said display device.
 15. A system of the type described in claim 14 wherein said range controlling means includes means for controlling the amount by which said given value is decremented, and means for controlling the predetermined quantity successively added to the resulting reference value.
 16. A system of the type described in claim 14 including means for displaying an alpha-numeric indication of the selected stock, the close price, and the range of values being displayed.
 17. A system of the type described in claim 13 wherein there are a fixed number of display positions on said display device at which a last-price value may be displayed; and including means responsive to the receipt of a new last price for said selected stock when all of said display positions are full for displaying the new value in the position previously occupied by the most recently received of the displayed values, for shifting all the displayed values one display position in the appropriate direction, and for eliminating the oldest displayed value from the display.
 18. A system of the type described in claim 1 including means for displaying alpha-numeric information with said graphic representation.
 19. A system of the type described in claim 1 wherein the normal display on said display device is the drawing of a line; and wherein said predetermined change causing means includes means for terminating the drawing of said line in response to a match in said comparing means.
 20. A system of the type described in claim 19 including means for defining a horizontal axis for said display; means for tracing a vertical line on said display device starting at said horizontal axis; and wherein said line drawing terminating means is operative to terminate the drawing of said line.
 21. A system of the type described in claim 20 wherein there are a plurality of said values to be graphically represented and including means for applying representations of said values in succession to said value representations storing means; said line drawing means being operative to draw a line starting at said horizontal axis for each of said values.
 22. A system of the type described in claim 21 wherein two different sets of values are to be simultaneously displayed on said display device; wherein one of said sets of values is displayed by drawing lines starting at said horizontal axis which are terminated in response to a match in a first comparing means; and wherein said second set of values is represented by displaying a point on said display device in response to a match in a second comparing means.
 23. A system of the type described in claim 22 wherein said two sets of values are related with corresponding values in each of said sets being displayed on the same vertical line; and including means for uniquely identifying a point where the two values on a common vertical line intersect.
 24. A system of the type described in claim 23 wherein said means for uniquely identifying includes means for inhibiting the display at a point where a point representing a value of said second set occurs on a line representing a line of said first set.
 25. A system of the type described in claim 21, wherein the values to be displayed are applied to said system as a cumulative amount; and including means responsive to the receipt of a new value for transferring the value in said value representation storing means to said reference value storing means.
 26. A system of the type described in claim 22 wherein said first set of values are volume values for succeeding transactions on a selected stock; and wherein said second set of values are last price values for said transactions.
 27. A system of the type described in claim 1 wherein said graphic representation is of two related values; and including separate means for storing a representation of each of said values; means for comparing the added to reference value with each of said representations; means responsive to a match between said added to reference value and a first of said stored representations for initiating the drawing of a line on said display device; and means responsive to a match between said added-to reference value and the other of said stored representations for terminating the drawing of the line on said display device.
 28. A system of the type described in claim 27 wherein said graphic representation is of three related values; wherein there is a separate one of said storing means and a separate one of said comparing means for each of the three values; and including means responsive to a match between said added-to reference value and the third of said values for causing a unique mark to appear on said line.
 29. A system of the type described in claim 28 wherein said line is a vertical line; and wherein said unique mark is a short horizontal line intersecting said vertical line.
 30. A system of the type described in claim 28 wherein said three values are the low price, high price, and last price respectively for a selected stock during a predetermined period of time.
 31. A system of the type described in claim 27 wherein said display is of at least two sets of related values; and including means for applying succeeding corresponding values from each of said sets in succession to the appropriate value representation storing means.
 32. In a CRT of the type having a raster scan with a plurality of index point containing strokes for each row displayed on the CRT screen, a system for displaying a graphic representation of a value comprising: means for storing a representation of said value; means for storing a reference value which is initially less than said representation; means for successively increasing said reference value in steps of predetermined quantity in synchronism with said raster moving past the index points of a stroke: means for comparing the increased reference value with said representation; and means responsive to a match in said comparing means for causing a predetermined indication to appear on said CRT at the index point being scanned at the time of said match.
 33. A system of the type described in claim 32 including means operative between the displayed portion of successive strokes for restoring the initial reference value in said reference value storing means.
 34. A method of displaying a graphic representation of a value on a CRT of the type having a raster scan with a plurality of index point containing strokes for each row displayed on the CRT screen comprising the steps Of: storing a reference value which is initially less than said representation; successively increasing said reference value in steps of predetermined quantity in synchronism with said raster moving past index points of a stroke; comparing the increased reference value with said representation; and generating a predetermined indication on said CRT at the index point being scanned when a match is detected during said comparing step.
 35. A method of the type described in claim 34 including the step of restoring the initial reference value during the time interval between the displayed portion of successive strokes. 